Effect of Ti Substitution on Thermoelectric Properties
of W-Doped Heusler Fe2VAl Alloy |
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Authors: | M Mikami K Ozaki H Takazawa A Yamamoto Y Terazawa T Takeuchi |
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Affiliation: | 1. National Institute of Advanced Industrial Science and Technology, Nagoya, 463-8560, Japan 2. National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8568, Japan 3. Department of Applied Physics, Nagoya University, Nagoya, 464-8603, Japan
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Abstract: | Effects of element substitutions on thermoelectric properties of Heusler Fe2VAl alloys were evaluated. By W substitution at the V site, the thermal conductivity is reduced effectively because of the enhancement of phonon scattering resulting from the introduction of W atoms, which have much greater atomic mass and volume than the constituent elements of Fe2VAl alloy. W substitution is also effective to obtain a large negative Seebeck coefficient and high electrical conductivity through an electron injection effect. To change the conduction type from n-type to p-type, additional Ti substitution at the V site, which reduces the valence electron density, was examined. A positive Seebeck coefficient as high as that of conventional p-type Fe2VAl alloy was obtained using a sufficient amount of Ti substitution. Electrical resistivity was reduced by the hole doping effect of the Ti substitution while maintaining low thermal conductivity. Compared with the conventional solo-Ti-substituted p-type Fe2VAl alloy, the ZT value was improved, reaching 0.13 at 450 K. |
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